PTHH: \(C_2H_4+Br_2\rightarrow C_2H_4Br_2\)
Ta có: \(n_{Br_2}=n_{C_2H_4}=\dfrac{4}{160}=0,025\left(mol\right)\) \(\Rightarrow V_{C_2H_4}=0,025\cdot22,4=0,56\left(l\right)\)
\(\Rightarrow V_{CH_4}=2,24\left(l\right)\)
\(\Rightarrow\left\{{}\begin{matrix}\%V_{CH_4}=\dfrac{2,24}{2,8}\cdot100\%=80\%\\\%V_{C_2H_4}=20\%\end{matrix}\right.\)